Quote Originally Posted by HeathBar View Post
A box pleat is what I had in mind. What is "fulled"?
Brief description in Wikipedia is accurate as as far as I know. Historical descriptions are quite colorful.

I think the result is similar to felting a knitted fabric (as for a tam), making it denser and thicker. If you've ever seen a wool sweater that was machine-washed at too high a temperature, that's felting!